1. Field of the Invention
The present invention relates to a solid-state imaging device that is an example of an semiconductor device for detecting a physical quantity distribution, an imaging apparatus, and an electronic apparatus, and, more particularly to a mechanism that sequentially outputs signals to other function units and to the outside (e.g., by horizontally transferring the signals).
2. Description of the Related Art
In the field of electric circuits, electric signals generated by a certain function unit are often sequentially transferred to other function units and to the outside (e.g., by horizontal transfer).
For example, a physical quantity distribution detecting semiconductor device configured by arraying plural unit elements (e.g., pixels), which have sensitivity to a change in a physical quantity of an electromagnetic wave inputted from the outside such as light or a radiation, a pressure (contact, etc.), or the like, in a matrix shape is used in various fields.
As an example, in the field of video apparatuses, a solid-state imaging device including an imaging element (an imaging device) of a CCD (Charge Coupled Device) type or a MOS (Metal Oxide Semiconductor) or CMOS (complementary Metal-oxide Semiconductor) type, which detects a change in light (an example of an electromagnetic wave) as an example of a physical quantity, is used.
In recent years, as an example of the solid-state imaging device, MOS and CMOS image sensors that can overcome various problems inherent in a CCD image sensor attract attention. In the field of computer apparatuses, a fingerprint authentication device and the like that detect an image of a fingerprint on the basis of a change in an electric characteristic or a change in an optical characteristic based on a pressure are used. These devices read out a physical quantity distribution, which is converted into an electric signal by unit elements (pixels in the solid-state imaging device), as an electric signal.
For example, the CMOS image sensor has, for each of pixels, an amplifier circuit configured by a floating diffusion amplifier and the like. In reading out a pixel signal, a system called a column parallel output type or a column type is often used. The column parallel output system or the column system is a system for, as an example of address control, selecting a certain row of a pixel array unit, simultaneously accessing pixels in the one row, and reading out pixel signals from the pixel array unit simultaneously and in parallel for all the pixels in the one row.
In the solid-state imaging device, a system for converting analog pixel signals read out from the pixel array unit into digital data with an analog-digital converter and then outputting the digital data to the outside may be adopted.
The same is true for the solid-state imaging device of the column parallel output type. Various signal output circuits have been devised as a signal output circuit for the solid-state imaging device. As an example of a most advanced form of the signal output circuits, a system that includes an AD converter for each of columns and takes out image information to the outside as digital data is considered (see, for example, W. Yang et al., “An Integrated 800×600 CMOS image system”, ISSCC99 DIGEST OF TECHNICAL PAPERS, SESSION 17/PAPER WA17.3, pp. 304 to 305, February, IEEE, 1999 (herein after referred to as Non-Patent Document 1).
As the AD conversion system, various systems have been considered from viewpoints of a circuit size, processing speed (an increase in speed), resolution, and the like. As an example, there is an AD conversion system called a slope integration type or a ramp signal comparison type (in this specification, hereinafter referred to as reference signal comparison type) for comparing an analog unit signal with a so-called ramp-like reference signal (a ramp wave), a value of which gradually changes, for converting the unit signal into digital data, performing count processing in parallel to this comparison processing, and acquiring the digital data of the unit signal on the basis of a count value at a point when the comparison processing is completed. In the Non-Patent Document 1, a configuration example adopting the AD conversion system of the reference signal comparison type is disclosed. Analog outputs from pixels can be subjected to AD conversion in column parallel in a low band. It can be said that this is suitable for an image sensor that realizes both a high image quality and high speed.